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O: Fachverband Oberflächenphysik
O 108: Electron-Driven Processes at Surfaces and Interfaces
O 108.7: Vortrag
Donnerstag, 19. März 2020, 16:30–16:45, TRE Ma
Simulating Electromigration in Metallic Atomic Contacts — •Markus Ring1, Fabian Pauly1,2, and Peter Nielaba1 — 1Universität Konstanz, Konstanz, Deutschland — 2Okinawa Institute of Science and Technology, Okinawa, Japan
This talk presents the results of ab-initio simulations of metallic contacts with the aim to understand current-induced structure changes and switching. To do this the effect of the electronic motion is integrated into a Langevin equation for the atoms.
The metallic contacts are investigated with density functional theory (DFT) for the atomic and electronic structure as well as the interaction between the two. All of these properties are calculated perturbatively with nonequilibrium Green’s function methods to determine transport properties. Among those properties are current-induced forces acting on the atoms. Those forces are modeled in a Langevin equation for the atoms, whose dynamics and kinetics are analyzed.
The primary results are threshold voltages at which vibration modes of the system turn unstable in the presence of non-equilibrium transport. These threshold voltages are investigated for a significant sample of contact realisation changing distance an lead structure for four metals (Pb, Au, Al, Cu) and compared with experimental switching voltages. Finally the unstable vibration modes are used to search and find additional stable conductance states. Overall this is an approach to bridging the time-scale gap between electronic and atomic motion and simulating switching and electromigration of atomic contacts from first principles.